Sandwich panels are typically formed from a core sandwiched between two face sheets. The core may be relatively thick, yet lightweight, as compared to the face sheets. The face sheets may be relative thin, yet stiff. Therefore, sandwich panels typically possess relatively high strength and stiffness at relatively low weight.
Because of their relatively high strength and stiffness at relatively low weight, sandwich panels are widely used in various aerospace applications. For example, sandwich panels are used in the construction of aircraft, such as commercial aircraft. Specifically, sandwich panels are used as the flooring, walls and bulkheads that define the passenger cabin of an aircraft. Therefore, such sandwich panels often are connected to the airframe of the aircraft such that loads applied to the sandwich panels are transferred to the airframe.
Connecting a sandwich panel to an airframe is typically effected with mechanical fasteners, such as bolts, that engage threaded inserts connected to the sandwich panel. The threaded inserts are typically potted (with an adhesive) into appropriately sized holes formed in the sandwich panel. The adhesives commonly used require long cure times, add undesired weight, and offer only limited pull strength protection since the load is transferred to the panel only through the adhesive. Also, care must be taken such that the threaded inserts are not placed too high in the holes relative to the outer surface of the associated face sheet, which may result in a gap being formed, or placed too low in the holes relative to the outer surface of the associated face sheet, which may result in unintentional pullout during tightening of the mechanical fastener.
Accordingly, those skilled in the art continue with research and development efforts in the field of sandwich panels.